Various kinds of devices have been proposed for drawing the center lines and other signs on the road surface. However, none of the conventional devices satisfies those requirements such as (1) a capability to draw lines having a fixed width and thickness of paint all through the lines, (2) a reliability of paint adhesion to the road surface, and (3) simplicity in the structure of the devices. In addition, with the conventional devices, it is difficult to apply a paint having a high viscosity onto the road surface. Further, the paint lines produced using a conventional air spray type device have such disadvantages as shown in FIGS. 1 and 2. In FIG. 1 the line has a portion a in which the paint is more thickly accumulated than in the other portions including side end portions b which look like a tail. In FIG. 2, the line also has a portion a in which the paint is more thickly accumulated than in the other portions including portions c in which the paint is thinly applied so that the edge portions of the line are not clear. It is therefore difficult to obtain a clear and uniform line on the road surface.
In order to overcome the above mentioned disadvantages, there has been filed U.S. patent application Ser. No. 538,966, filed Jan. 6, 1975, now U.S. Pat. No. 3,960,326, which has been assigned to the same assignee as that of this application. The apparatus of the U.S. patent application Ser. No. 538,966 now U.S. Pat. No. 3,960,326 comprises a paint supply means incorporating therein a valve means and provided with a plurality of orifices in two rows in an opposite relation on a lower portion of said paint supply means for paint discharging, a tank communicating with said paint supply means for containing a paint, and a pair of wire roll brushes attached to said paint supply means to rotate inwardly and touch said orifices.
The present invention is concerned with the improvement of the apparatus of the U.S. patent application Ser. No. 538,966. According to the present invention, the improvements in efficiency and durability can be attained. For example, in the present invention, there are employed in place of the wire roller brushes of the copending patent application Ser. No. 538,966 a pair of roller members each provided at the external periphery thereof with a plurality of projections having shapes like saw teeth in cross section, whereby the paint having a high viscosity can be discharged sufficiently and effectively.
Accordingly, an object of the present invention is to provide an apparatus for paint application including a pair of rollers each provided at the external periphery with a vast plurality of projections extending in the axial direction of the roller and having shapes like saw teeth in cross section, a plurality of orifices formed in two rows in an opposite relation on a lower portion of said supply means for paint discharging and a pair of cover members mounted on an external portion of the paint supply means, whereby the paint having a high viscosity can be discharged sufficiently and efficiently to draw the lines having a fixed width and uniform thickness without regard of the rise and fall of the road surface and the distance between the apparatus and the road surface.
Another object of the present invention is to provide an apparatus for paint application which is simple in structure and durable.
Essentially, according to the present invention, there is provided an apparatus for paint application comprising a paint supply means incorporating therein a valve means and provided, on its lower portion, with a plurality of paint discharging orifices in two rows in an opposite relation, a tank communicating with said paint supply means for containing a paint, a pair of rollers each provided at the external periphery thereof with a vast plurality of projecting teeth extending in the axial direction of the roller and grooves formed side by side with the projecting teeth, said rollers being attached to said paint supply means to rotate inwardly and located adjacent said orifices, and a pair of cover members each of which is connected at its one end to the external surface of said paint supply means to cover the roller and has, at its other end, an edge portion which is disposed adjacent the lower side of said roller.